A mechanism for adsorbing and holding a substrate has conventionally been used in the process of manufacturing semiconductor substrates (hereinafter, simply referred to as “substrates”). When there is a warp in a substrate, the mechanism for adsorbing and holding a substrate may not be able to adsorb the substrate suitably.
In view of this, Japanese Patent Application Laid-Open No. 2012-119464 (Document 1) proposes a wafer holding device that adsorbs a substrate after correcting a warp in the substrate. Specifically, the wafer holding device holds a wafer on the upper edge portion of a cup-shaped suction guard by suction and moves the suction guard down so as to press the wafer against a flat plate-like correcting part disposed in the suction guard. Accordingly, the warp in the wafer is corrected, and the shape of the wafer is approximated to a flat shape. Thereafter, a suction chuck is moved upward to come in contact with the lower surface of the wafer so that the wafer is adsorbed and held by the suction chuck.
The wafer holding device of Document 1 requires various configurations for adsorbing a wafer after correcting a warp in the wafer and also requires a mechanism for moving such configurations up and down individually. Thus, the device structure may be complicated. When there is a relatively large warp in a wafer, the wafer may be damaged in the process of pressing the wafer against the correcting part to correct the warp in the wafer.